It's not 50 mm thick, you're (probably) thinking about the lower glacis of the Challenger 2, which is just as thin and thus required add-on ERA for combat (it was pretty useless though given that the RPG-29 managed to get through the whole set up).

No one for sure knows how thick the glacis of the Abrams is, but like you mentioned, we do know it's about 600 mm of RHAe against KE and almost 1,000 mm of RHAe against CE. Either way, it's too 'good' to be simply 50 mm thick, closer to 400 mm or so given what we know about the compositions in use.

Hi everyone, I read that the M1A1/A2 glacis armor is only ~50mm of RHA but sloped at very small angle from horizontal (7-10 degrees I think) so that solves the problem as the LOS is very high with the slope. But, I have noticed something, by looking at the pictures : http://2.bp.blogspot...3_30_Abrams.jpghttp://1.bp.blogspot...1600/m1a103.jpg ......You can see that any small ricochet would make something like APFSDS penetrator hit the turret ring, which is very weak if I'm not mistaken, compared to the very well armored turret. So isn't this a shot trap like the one the KT tank suffered with its old turret during WW2 ?
I just feel that there is something I misunderstand, because it is impossible that the designers never noticed that!!
So what do you guys think ?

It actually is some sort of shot trap. But not because the probability of hitting it (directly or via ricocheting) is very high (modern ammunition is still not that accurate), but medium caliber guns with a high rate of fire could jam the turret. Some other tanks have been fitted with extra protection of the turret.

Hurricane939, on Sep 14 2012 - 02:27, said:

Actually it is 600 RHAe (Equivalent), but the real thickness is just 50mm.

No. The glacis plate is only two inches thick and only equivalent to two inches steel armour at that angle (8° from the horizontal) - this will be 365 mm steel. However the angle (8°) is so small, that even the latest APFSDS ammunition ricochets. Modern HEAT ammunition (RPGs and tank rounds) fails to fuze at angles samller than 15°, so the glacis plate is simply immune to APFSDS and HEAT ammunition. However if the tank is driving a slope down, the hull armour is exposed and vulnerable to everything larger than a 25 mm APDS from ranges exceeding a mile (25 mm APDS will penetrate at 1,200 m or 3/4 mile when hitting from 90°).
The part that is "somehow" equivalent to 600 mm RHA is the lower hull front and the "nose plate". This armour is about two feet thick, so it will probably be slightly less protective than two feet RHA against APFSDS and significantly stronger than two feet steel against HEAT ammunition.

IronsightSniper, on Sep 14 2012 - 08:53, said:

It's not 50 mm thick, you're (probably) thinking about the lower glacis of the Challenger 2, which is just as thin and thus required add-on ERA for combat (it was pretty useless though given that the RPG-29 managed to get through the whole set up).

Glacis is always used to refer to the upper sloped plate of a tank hull. The lower plate is not the glacis.

No. The glacis plate is only two inches thick and only equivalent to two inches steel armour at that angle (8° from the horizontal) - this will be 365 mm steel. However the angle (8°) is so small, that even the latest APFSDS ammunition ricochets. Modern HEAT ammunition (RPGs and tank rounds) fails to fuze at angles samller than 15°, so the glacis plate is simply immune to APFSDS and HEAT ammunition. However if the tank is driving a slope down, the hull armour is exposed and vulnerable to everything larger than a 25 mm APDS from ranges exceeding a mile (25 mm APDS will penetrate at 1,200 m or 3/4 mile when hitting from 90°).
The part that is "somehow" equivalent to 600 mm RHA is the lower hull front and the "nose plate". This armour is about two feet thick, so it will probably be slightly less protective than two feet RHA against APFSDS and significantly stronger than two feet steel against HEAT ammunition.

That's exactly what I'm talking about, I'm not saying the glacis is too weak so it will be penetrated easily, no. What I'm saying is that it is too sloped that it would not fuze ATGMs and ricochet almost everything to hit the turret ring, which would not only jam the turret in this case, by destroy the whole tank in case of penetration. Not to mention the glacis being shot somewhere higher than the tank level, such as a gunship or even someone with RPG at a roof of a building.

It's not 50 mm thick, you're (probably) thinking about the lower glacis of the Challenger 2, which is just as thin and thus required add-on ERA for combat (it was pretty useless though given that the RPG-29 managed to get through the whole set up).

No one for sure knows how thick the glacis of the Abrams is, but like you mentioned, we do know it's about 600 mm of RHAe against KE and almost 1,000 mm of RHAe against CE. Either way, it's too 'good' to be simply 50 mm thick, closer to 400 mm or so given what we know about the compositions in use.

Like others have stated, ricochets aren't likely to happen nowadays.

I found a picture for you : http://chivethebriga...tank-920-24.jpg .. it shows you how "thick" the glacis is. calculating the slope gives you about 400mm LOS, so I don't find it hard that the compositions makes it 1.5X against KE and 2.5X against CE, that is pretty normal according to what I know, or else how could they have managed to make 2000mm RHAe for the Leo 2 turret with not very sloped armor.

That's exactly what I'm talking about, I'm not saying the glacis is too weak so it will be penetrated easily, no. What I'm saying is that it is too sloped that it would not fuze ATGMs and ricochet almost everything to hit the turret ring, which would not only jam the turret in this case, by destroy the whole tank in case of penetration. Not to mention the glacis being shot somewhere higher than the tank level, such as a gunship or even someone with RPG at a roof of a building.

This is one example which shows that no tank is invulnerable. The always exaggerated performance of the M1 (in English-language forums, in Russian-language forums the performance is understated) makes most people believe that the M1 is somehow magically better than all other tanks. The weak glacis and roof armour are examples that the M1 is just a normal tank with it's special strengths and weaknesses. The Leopard 2 uses a similar glacis layout (also strongly sloped steel), while the Challenger 1 and 2 have a "death spot" at the drivers position. It would be possible to create a tank without such a gap in the turret ring or at least a smaller one (see Leopard 2), but then the driver would need to be relocated.

Hurricane939, on Sep 14 2012 - 11:16, said:

I found a picture for you : http://chivethebriga...tank-920-24.jpg .. it shows you how "thick" the glacis is. calculating the slope gives you about 400mm LOS, so I don't find it hard that the compositions makes it 1.5X against KE and 2.5X against CE, that is pretty normal according to what I know, or else how could they have managed to make 2000mm RHAe for the Leo 2 turret with not very sloped armor.

What you see there is a two inches homogenous steel plate. This does not have a higher thickness efficiency than 1 (and modern composite armour is also not stronger than it's thickness against KE). Slope is the reason why the thin glacis is considered as good:

This is one example which shows that no tank is invulnerable. The always exaggerated performance of the M1 (in English-language forums, in Russian-language forums the performance is understated) makes most people believe that the M1 is somehow magically better than all other tanks. The weak glacis and roof armour are examples that the M1 is just a normal tank with it's special strengths and weaknesses. The Leopard 2 uses a similar glacis layout (also strongly sloped steel), while the Challenger 1 and 2 have a "death spot" at the drivers position. It would be possible to create a tank without such a gap in the turret ring or at least a smaller one (see Leopard 2), but then the driver would need to be relocated.

What you see there is a two inches homogenous steel plate. This does not have a higher thickness efficiency than 1 (and modern composite armour is also not stronger than it's thickness against KE). Slope is the reason why the thin glacis is considered as good:

No reasonable estimate puts the Leopard 2 turret at 2,000 mm RHAe vs KE, only the latest versions vs CE. On for achieving this level of protection the Leopard 2 has 5 feet thick armour.

You are right, here : http://chivethebriga...tank-920-25.jpg .. this challenger 2 should pray nothing hits this area. But don't you think that the armor behind the driver periscope is very powerful ? I mean that small part of vertical armor.

And yea but still, a WW2 Anti-tank shell would ruin the abrams day if they hit any part of the glacis. Also, can you get me any source or a picture of tank with extra turret protection as you mentioned ?

I think a google image search should lead to numerous pictures of them and articles about them.

Hurricane939, on Sep 14 2012 - 11:48, said:

You are right, here : http://chivethebriga...tank-920-25.jpg .. this challenger 2 should pray nothing hits this area. But don't you think that the armor behind the driver periscope is very powerful ? I mean that small part of vertical armor.

No it is not. It is a small steel plate (there are some books which contain images from the production lines). One hit there and the Challenger is penetrated. One thing most people do not understand is that composite armour is nearly allways less efficient than steel of the same thickness (against KE, for CE it is different) - however composite armour weighs far less. One example is the earliest T-64. It had a cast turret with aluminium filler. The aluminium offers only 60% the protection of armour steel, but it weighs roughly a third of steel. Therefore the armour was more protective than normal steel armour for a given weight.
The strongest possible material against KE I know is high-hardness steel (HHS). However HHS is rather brittle (which means you cannot use it own your own) and does weight as much as normal steel (weight reduction is therefore only possible if you make the armour thinner). Ceramics are also good, but not by means of protection-per-thickness.

I think a google image search should lead to numerous pictures of them and articles about them.

No it is not. It is a small steel plate (there are some books which contain images from the production lines). One hit there and the Challenger is penetrated. One thing most people do not understand is that composite armour is nearly allways less efficient than steel of the same thickness (against KE, for CE it is different) - however composite armour weighs far less. One example is the earliest T-64. It had a cast turret with aluminium filler. The aluminium offers only 60% the protection of armour steel, but it weighs roughly a third of steel. Therefore the armour was more protective than normal steel armour for a given weight.
The strongest possible material against KE I know is high-hardness steel (HHS). However HHS is rather brittle (which means you cannot use it own your own) and does weight as much as normal steel (weight reduction is therefore only possible if you make the armour thinner). Ceramics are also good, but not by means of protection-per-thickness.

So by that you mean that the Abrams has LITERAL 700-900mm armor at the turret or even more since you said composite armor is less efficient than steel of the same thickness ?

So by that you mean that the Abrams has LITERAL 700-900mm armor at the turret or even more since you said composite armor is less efficient than steel of the same thickness ?

Yes. The exact thickness depends on whom you ask. Measuring of thickness can only be made by measuring images or drawings (unless you have access to a real M1A2). Russians typically put the turret front at 800 - 850 mm thickness (and they claim that this will offer some protection equivalent to 700 mm RHA vs KE). Some Westerners claim that the armour is thicker (Wikipedia says that it is 880 mm thick, but some people estimate the thickness at 950 mm; this is said to offer 800 - 900 mm RHAe protection vs KE). Curiosly both Westerners and Russians base this values on images or drawings under the assumption that these are for scale. If the drawings however are not for scale the values are wrong.
The T-72B (from 1984/5) has 815 mm thick armour (based on a book) and on some other forums you might find photos were some soldier actually measures the armour of a Leopard 2A4, which is 800 mm thick + innermost steel plate.
It is known from Zaloga's writings that the earliest models (pre-IPM1) had 9 inches thinner armour.

Yes. The exact thickness depends on whom you ask. Measuring of thickness can only be made by measuring images or drawings (unless you have access to a real M1A2). Russians typically put the turret front at 800 - 850 mm thickness (and they claim that this will offer some protection equivalent to 700 mm RHA vs KE). Some Westerners claim that the armour is thicker (Wikipedia says that it is 880 mm thick, but some people estimate the thickness at 950 mm; this is said to offer 800 - 900 mm RHAe protection vs KE). Curiosly both Westerners and Russians base this values on images or drawings under the assumption that these are for scale. If the drawings however are not for scale the values are wrong.
The T-72B (from 1984/5) has 815 mm thick armour (based on a book) and on some other forums you might find photos were some soldier actually measures the armour of a Leopard 2A4, which is 800 mm thick + innermost steel plate.
It is known from Zaloga's writings that the earliest models (pre-IPM1) had 9 inches thinner armour.

Great, thanks.
So do you have any idea about the weight of composite armor compared to RHA ? Since something like 800mm of actual steel at the turret would make the tank too heavy to move not the mention the rest of the armor.

It's not 50 mm thick, you're (probably) thinking about the lower glacis of the Challenger 2, which is just as thin and thus required add-on ERA for combat (it was pretty useless though given that the RPG-29 managed to get through the whole set up).

Yes, it blew off the drivers toe.....didn't knock out the vehicle. This was one of the most modern AT missile out there when it got hit and penetrated the weakest part of the frontal armour of the Challenger 2 so don't get all excited. The vehicle still drove away with a 9 toe driver and brown trousers. Its not clear whether this incident occurred prior to the frontal armour upgrade either so it may just have struck the hull rather than the add-on armour. Also if it had penetrated the add-on armour a variation package would have changed the composition of it to prevent it happening again and I see no changes to the the add-on armour package used subsequently. (although the changes may have been to composition inside the armour pacage and may not be visible)

Here the same missile hit what is supposed to be the strongest part of the frontal armour of an M1 and penetrated injuring the crew.

Spoiler

.

The glacis armour and upper hull armour at the front on the Abrams is not exactly thick: zoom in on this photo to see the end of the glacis plate on the Abrams to see how thick it is and the upper hull portion as well. You also get an idea of how far up the collar from the hull is for keeping the turret on. although in this case the turret was blown off.

Spoiler

.

The RPG used against that Challenger was an RPG-29, this Abrams though was penetrated through its side by an RPG7VR in 2003 injuring the crew: (white paper covers hole)

Spoiler

.

In fact the RPG was powerful enough that having damaging various surfaces and crew inside it then penetrated nearly 2 inches in the other side of the hull.

Spoiler

.

Hurricane939, on Sep 14 2012 - 11:48, said:

You are right, here : http://chivethebriga...tank-920-25.jpg .. this challenger 2 should pray nothing hits this area. But don't you think that the armor behind the driver periscope is very powerful ? I mean that small part of vertical armor.

That 'dead zone' you mention is actually better because it provides cover around the drivers hatch which like all hatches on all tanks is a significant weak point and allow for extra armour at the back of the glacis and over the ammunition stowage which on the Challenger is in the hull for safety reasons and is well armoured.
If you compare the gap between the hull and the turret on the M1 and the Chellenger you'll see that the hull design of the Challenger eliminates much of that gap at the front, hence that 'dead zone' you were talking about.

You can see the gap is much larger on the M1 and that the front of the turret overhangs the front of the hull much more.

Regarding the turret ring on a modern tank: this is the thickness of the turret ring shown on the turret on a knocked out M1A2SEP in Iraq showing just how thick the turret ring is. I dont see anything other than a large caliber round or very lucky RPG penetrating this:

Spoiler

.

Here an RPG has penetrated the side of the M1's turret and caused the ammunition in the back of the turret to detonate: (you can also see the thickness of the hull and glacis plates quite clearly.

Yes, it blew off the drivers toe.....didn't knock out the vehicle. This was one of the most modern AT missile out there when it got hit and penetrated the weakest part of the frontal armour of the Challenger 2 so don't get all excited. The vehicle still drove away with a 9 toe driver and brown trousers. Its not clear whether this incident occurred prior to the frontal armour upgrade either so it may just have struck the hull rather than the add-on armour. Also if it had penetrated the add-on armour a variation package would have changed the composition of it to prevent it happening again and I see no changes to the the add-on armour package used subsequently. (although the changes may have been to composition inside the armour pacage and may not be visible)

Here the same missile hit what is supposed to be the strongest part of the frontal armour of an M1 and penetrated injuring the crew.

Spoiler

.

The glacis armour and upper hull armour at the front on the Abrams is not exactly thick: zoom in on this photo to see the end of the glacis plate on the Abrams to see how thick it is and the upper hull portion as well. You also get an idea of how far up the collar from the hull is for keeping the turret on. although in this case the turret was blown off.

Spoiler

.

The RPG used against that Challenger was an RPG-29, this Abrams though was penetrated through its side by an RPG7VR in 2003 injuring the crew: (white paper covers hole)

Spoiler

.

In fact the RPG was powerful enough that having damaging various surfaces and crew inside it then penetrated nearly 2 inches in the other side of the hull.

Spoiler

.

That 'dead zone' you mention is actually better because it provides cover around the drivers hatch which like all hatches on all tanks is a significant weak point and allow for extra armour at the back of the glacis and over the ammunition stowage which on the Challenger is in the hull for safety reasons and is well armoured.
If you compare the gap between the hull and the turret on the M1 and the Chellenger you'll see that the hull design of the Challenger eliminates much of that gap at the front, hence that 'dead zone' you were talking about.

You can see the gap is much larger on the M1 and that the front of the turret overhangs the front of the hull much more.

Regarding the turret ring on a modern tank: this is the thickness of the turret ring shown on the turret on a knocked out M1A2SEP in Iraq showing just how thick the turret ring is. I dont see anything other than a large caliber round or very lucky RPG penetrating this:

Spoiler

.

Here an RPG has penetrated the side of the M1's turret and caused the ammunition in the back of the turret to detonate: (you can also see the thickness of the hull and glacis plates quite clearly.

Spoiler

.

No tank is invulnerable.

edit:images fixed

So where do the designers expect most of the hits from the enemy to hit ? the lower hull ? or the turret ?!!
Also, aren't the designers aware of this weakspot ? why don't they put something like a "collar" to reduce this gap ?!!
It just makes me very angry to know that some WW2 lucky shots at THE FRONTAL ABRAMS ARMOR can just deflect on its glacis armor and destroy it. And still, modern HEAT rounds can deflect and change their pass, and hit this weak area because they can't fuze at such slope. Also, something like 30mm gun like the one the A-10 uses can be the worst nightmare to the Abrams in my opinion.

So where do the designers expect most of the hits from the enemy to hit ? the lower hull ? or the turret ?!!

The turret is meant to be the heaviest protected part esp[ecially the front as these were meant to be the only bit sticking up when in a defensive hull down position. The frontal area on the Abrams is a bigger target than many contemporaries and has been uparmoured more than once because....... it clearly wasn't sufficient for the perceived threat.

Hurricane939, on Sep 14 2012 - 18:09, said:

Also, aren't the designers aware of this weakspot ? why don't they put something like a "collar" to reduce this gap ?!!

I'm sure they are ware, The point is that the Abrams is designed for the American concept of operation which has an emphasis on mobility at the expense of protection. There is a 'collar', there is armour under there but it is steel not chobham although probably laminated as well with a spall liner to boot. But there is no getting around the weakeness of all turreted tanks to the join between hull and turret.
This gap (vulnerability) is larger on some vehicles than on others. Due to the low sloping glacis plate the tradeoff is that there has to be a larger gap to allow the driver to get out (look at the shape of the front corners of the turret as well to allow for egress). The Challenger and some opthers avoid this by raising the shoulders of the glacis to compensate keeping that gap reduced.

Hurricane939, on Sep 14 2012 - 18:09, said:

It just makes me very angry to know that some WW2 lucky shots at THE FRONTAL ABRAMS ARMOR can just deflect on its glacis armor and destroy it. And still, modern HEAT rounds can deflect and change their pass, and hit this weak area because they can't fuze at such slope. Also, something like 30mm gun like the one the A-10 uses can be the worst nightmare to the Abrams in my opinion.

Multiple hits from a HE cannon or the DU rounds from an A-10 would be devastating to all tanks becuase of the area of damage, whether it could be knocked out and crew killed or just so sereveraly damaged as to be only fit for abandoning and burning is a different point. The hatches are now nomrally made out of titanium after a retro-fit program to reduce the vulnerability of the hatches to fire and feature a spaced armour slab on top as well.

All in all IMO whilst the abrams is a vary capable tank it suffered from the 'designed by committee' syndrome which hamstrung the Bradley AFV. It had to be light enough for the Marines and heavy enough for the Army but fast enough to get to where doctrine wanted and heavily armoured enough to trade blows with contemporary enemy tanks envisaged in the late 1970's and early 1980's.
The net result is a vehicle which is a very competant tank which although weighing nearly as much as its contemporaries I have always seen as more of a heavy-medium tank rather than a true heavy tank. (yes i know we use the term MBT now but you get my point)
It has been through numerous retro-fit and improvement programs and still is shown to be too vulnerable to RPG hits.
There is no money now though to develop a new heavy-heavy tank to fill this need. The Abrams suffers the same flaws as the Leopard in being designed too light, the Challenger which was always designed very heavy (too heavy it was said at the time) suffers less needing less add-on armour but with an in-service date of until about 2030 or something will probably outlast some of its comtemporaries but will be outdated before then.
I think in light of the tatctics of huge IED's and multiple RPG ambush attacks on tanks we will see the end of the heavy-medium tanks like the Leopard and abrams.
The Merkava (another fan-boy favourite on the internet) is specific for the Israeli theater of operation and has proven woefully vulnerable to even single rrpg hits and present an almost unmissable frontal target (but it is very cheap compared to its contemporaries). I think the Merkava is probably the most over-rated tank ever based on theroies of tank design from the 1960's.
It's always going to be difficult to do any sensible assessment of a tank though due to nationalistic rantings. You just have to look with an impartial eye at which one you would want your son to go to war in. I know which one I would prefer them to be in.

Great, thanks.
So do you have any idea about the weight of composite armor compared to RHA ? Since something like 800mm of actual steel at the turret would make the tank too heavy to move not the mention the rest of the armor.

This is case specific, but it should be generally less. The T-64 turret with the aluminium filler should weigh something about 50-70% as much as a steel turret of the same thickness. But that's very primitive armour.

Vollketten, on Sep 14 2012 - 16:10, said:

Yes, it blew off the drivers toe.....didn't knock out the vehicle. This was one of the most modern AT missile out there when it got hit and penetrated the weakest part of the frontal armour of the Challenger 2 so don't get all excited. The vehicle still drove away with a 9 toe driver and brown trousers. Its not clear whether this incident occurred prior to the frontal armour upgrade either so it may just have struck the hull rather than the add-on armour. Also if it had penetrated the add-on armour a variation package would have changed the composition of it to prevent it happening again and I see no changes to the the add-on armour package used subsequently. (although the changes may have been to composition inside the armour pacage and may not be visible)

Here the same missile hit what is supposed to be the strongest part of the frontal armour of an M1 and penetrated injuring the crew.

Spoiler

.

As you can see it did not travel through the strongest part of the armour of the M1. The pictured tank btw. is not a M1A2 and therefore not comparable with the Challenger 2 in terms of sophistication of armour.

Vollketten, on Sep 14 2012 - 16:10, said:

The RPG used against that Challenger was an RPG-29, this Abrams though was penetrated through its side by an RPG7VR in 2003 injuring the crew: (white paper covers hole)

Spoiler

.

In fact the RPG was powerful enough that having damaging various surfaces and crew inside it then penetrated nearly 2 inches in the other side of the hull.

Spoiler

.

The side of no modern tank can resist a RPG without being uparmoured (bar the Merkava IV maybe, which has more side armour than other tanks). This is nothing special.

Vollketten, on Sep 14 2012 - 16:10, said:

That 'dead zone' you mention is actually better because it provides cover around the drivers hatch which like all hatches on all tanks is a significant weak point and allow for extra armour at the back of the glacis and over the ammunition stowage which on the Challenger is in the hull for safety reasons and is well armoured.
If you compare the gap between the hull and the turret on the M1 and the Chellenger you'll see that the hull design of the Challenger eliminates much of that gap at the front, hence that 'dead zone' you were talking about.

The weakened area on the Challenger 1/2 is easier to hit, because it does have a greater size. The M1's turret gap is wider, but does have only 1/3 to 1/2 of the height. The result is probably similar large "weak zones", with the Challenger's weak zone being more focused.

Vollketten, on Sep 14 2012 - 19:46, said:

The turret is meant to be the heaviest protected part especially the front as these were meant to be the only bit sticking up when in a defensive hull down position. The frontal area on the Abrams is a bigger target than many contemporaries and has been uparmoured more than once because....... it clearly wasn't sufficient for the perceived threat.

This has also to do with the fact that the M1 remained (and is planned to remain) longer in service. When the original requirements for armour protection were made during the M1 development (at this time not even wearing the name XM1) the Soviet Union was not even known to have a 125 mm smoothbore gun. This is why the first version of the M1 did have less armour than the IPM1 or M1A1. Then the Soviets started introducing tungsten-cored and DU ammunition to counter the heavier NATO armour culminating in the 3BM-32 and 3BM-42 rounds. So the U.S. uparmoured their tanks again (M1A1HA). Then the Soviets developed monobloc tungsten and DU ammunition with increased length-to-diameter ratio, which lead again to a new generation of U.S. tank armour. This is simply actio and reactio and has nothing to do with the M1 being significantly weaker armoured than other tanks.
In a similar manner the Germans did change the armour on the Leopard 2 tanks, they just started a little bit higher (in terms of thickness and probably of protection), because they made up their requirements for armour protections a few years later than the U.S.
Just because the Challenger 1 was not uparmoured during the Cold War, this doesn't mean that it would have been able to resist contemporary Soviet ammunition. If we take a look at the L23 APFSDS, the only British 120 mm APFSDS used during the Cold War, we can see that it does not perform good enough to ensure penetration of contemporary Soviet tanks at normal ranges frontally.

Vollketten, on Sep 14 2012 - 19:46, said:

I'm sure they are ware, The point is that the Abrams is designed for the American concept of operation which has an emphasis on mobility at the expense of protection.

This is a myth. A typical overgeneralization which can be found in various internet discussions ("The Leopard 2 and the M1 Abrams can go as fast as 45 mph, while the Challenger can do only "). Take a look at the M47, M48, M60 tanks... are these tanks more mobile than their contemporaries? No. The U.S. and the FRG wanted during the development of the MBT-70 a tank better armoured, better armed and more mobile than any tank the Soviet could produce in the next decade(s).

Vollketten, on Sep 14 2012 - 19:46, said:

The net result is a vehicle which is a very competant tank which although weighing nearly as much as its contemporaries I have always seen as more of a heavy-medium tank rather than a true heavy tank. (yes i know we use the term MBT now but you get my point)

You are aware that (bar the Leopard 2) the M1 was the heaviest tank for half a decade after it was made?

As you can see it did not travel through the strongest part of the armour of the M1. The pictured tank btw. is not a M1A2 and therefore not comparable with the Challenger 2 in terms of sophistication of armour.

Why would the frontal armour of the turret not be the strongest part of the armour?

alternaive, on Sep 14 2012 - 20:55, said:

Just because the Challenger 1 was not uparmoured during the Cold War, this doesn't mean that it would have been able to resist contemporary Soviet ammunition. If we take a look at the L23 APFSDS, the only British 120 mm APFSDS used during the Cold War, we can see that it does not perform good enough to ensure penetration of contemporary Soviet tanks at normal ranges frontally.

I never mentioned the Challenger 1 which is a Chieftan tank with upgrades, The picture was of a Challnnger 2 which is a bespoke designed from scratch tank.

alternaive, on Sep 14 2012 - 20:55, said:

You are aware that (bar the Leopard 2) the M1 was the heaviest tank for half a decade after it was made?

Are you sure you're not confused about short and long tons compared to metric tonnes?

Why would the frontal armour of the turret not be the strongest part of the armour?

Did you look at your image? The RPG was launched from an elevated position - the penetration channel is sloped downwards. This way the HEAT jet had to travel through far less material. The HEAT jet did not exit the armour through the rear, but instead exited through the bottom of the armour box. So the heaviest armoured part was not penetrated.

Vollketten, on Sep 14 2012 - 21:28, said:

I never mentioned the Challenger 1 which is a Chieftan tank with upgrades, The picture was of a Challnnger 2 which is a bespoke designed from scratch tank.

The Challenger 1 is not based on the Chieftain. There were numerous different vehicles inbetween, like the MBT-80 and the ATR (which had the same armour layout as the Challenger 1). The Challenger 2 is not designed from the scratch, it is an updated Challenger 1 with a modified Vickers turret originally developed for the Vickers Mk 7.

Vollketten, on Sep 14 2012 - 21:28, said:

Are you sure you're not confused about short and long tons compared to metric tonnes?

Combat loaden the M1 was heavier than everything else existing (bar the Leopard 2) until the IPM1, Challenger 1 and finally the M1A1 were introduced. The M1 weighed roughly 1 tonne more than the Chieftain and the Leopard 2 roughly one tonne more than the M1.

This is an older pic without the elcctrical discharge anti-IED equipment fitted or bar armour over the rear hull.

This calls for sum Challenger 2 pr0n!KRH Challenger 2 by Dave Layland, on Flickr Note the lower hull ERA has been replaced by a block of peanut butter, and the two distinct layers of uparmouring on the side hull. Rumoured to contain both ERA and peanut butter.

Vollketten, on Sep 14 2012 - 21:28, said:

I never mentioned the Challenger 1 which is a Chieftan tank with upgrades, The picture was of a Challnnger 2 which is a bespoke designed from scratch tank.

More a product improved chally 1. If it was designed from scratch they sure moved quick after CAT 87, and it sure looks similar to the chally 1. 93% part uncommonality doesn't mean it isn't just slightly improved

alternaive, on Sep 14 2012 - 22:06, said:

The Challenger 1 is not based on the Chieftain. There were numerous different vehicles inbetween, like the MBT-80 and the ATR (which had the same armour layout as the Challenger 1).

Chieftain of a similar vintage does have exactly the same fire control system, and a very similar suspension design, and a very similar armour layout. In fact, it looks very similar to the "burlington chieftain"

Did you look at your image? The RPG was launched from an elevated position - the penetration channel is sloped downwards. This way the HEAT jet had to travel through far less material. The HEAT jet did not exit the armour through the rear, but instead exited through the bottom of the armour box. So the heaviest armoured part was not penetrated.

Yes, I saw it, the RPG round penetrated the frontal turret armour sufficiently that it went through into the vehicle compartment where it injured the crew. I fail to see your point. If the bottom 6 inches of armour on the turret dont count as armour why are they there?

Challenger 1 and 2 are different vehicles, I only say so because the firm that makes them says so, so I gfelt they were probably a decent source, you could ask Vickers about them if you like.

alternaive, on Sep 14 2012 - 22:06, said:

Combat loaden the M1 was heavier than everything else existing (bar the Leopard 2) until the IPM1, Challenger 1 and finally the M1A1 were introduced. The M1 weighed roughly 1 tonne more than the Chieftain and the Leopard 2 roughly one tonne more than the M1.

I think we need to see some numbers based in normal (kilograms) instead of just saying ton or tonne. Either way i agree with the original poster that the Abrams is underarmoured. I think the battle damage from Iraq bore this view out.